Fibroids: What They Are, Types, and Causes

What are fibroids?

Fibroids are benign (non-cancerous) growths within the uterine muscle. Fibroids are also known as myomas or leiomyomas.

How common are fibroids?

Fibroids are extremely common and approximately 50% of women will have fibroids. Most fibroids are small and asymptomatic, but 40% women with fibroids will present with some symptoms.

What causes fibroids?

The cause of fibroids is not known. Fibroids are more common in women who do not have children and also common in Afro-Caribbean women. Fibroids are known to be oestrogen dependent. That’s why they grow in size during pregnancy and shrink after menopause.

Why are fibroids more common in Afro-Caribbean women?

The exact cause is not known. There may be a genetic component to this. Some people believe that it is due to specific diet (such as Yam) but fibroids are common in native as well as immigrant Afro-Caribbean population.

What are the types of fibroids?

Fibroids can be classified as small (less than 4 cm), medium (4-8 cm) or large (greater than 8 cm). They are also classified depending on the location:

Submucous fibroids: Fibroids that grow inwards within the uterine cavity, more likely to cause bleeding problems, also more amenable to Hysteroscopic Surgery.

Intramural fibroids: Fibroids that grow within the wall of the uterus

Subserous fibroids: Fibroids that grow outwards, more likely to cause pressure symptoms. Intramural and subserous fibroids are more amenable to laparoscopic surgery.

Can fibroids be cancerous?

Fibroids are rarely malignant and the risk is approximately 1 in 1000. The risk is higher if the fibroids are growing rapidly or if they are extremely large or if they start growing after menopause. Cancerous fibroids are known as Leiomyosarcoma.